There are many instances in which visually handicapped persons need to be warned of their approach to a dangerous area. For example, it is critical in public areas to warn those persons of their proximity to uneven surface areas. Some examples of areas requiring such warning include train platform edges and sidewalk curbs, especially in the vicinity of cross-walks where the warning can also indicate the presence of a cross-walk.
There have been numerous attempts to provide such warning to visually handicapped persons. Most of those attempts employ tactile warning, often times along with some visual warning to which partially-sighted visually handicapped persons may be able to respond. Most of the tactile warning systems employ relatively small tiles having some type of uneven surface which the visually-handicapped person can detect with a cane or his or her feet. One such device is disclosed in U.S. Pat. No. 4,715,743. That device comprises tiles made of a flat plate of a flexible polymer material with a number of raised bumps formed of the same material and projecting from the surface. These tiles must be set in concrete or mortar in the areas in which warning is desired. In existing stations, concrete must be removed in order to create a setting bed for the tile and allow for a level installation. Accordingly, the tiles are difficult and expensive to install. Further, the area in which the tiles are installed may not be used by the public until the mortar is set, which can be a problem in areas such as train stations which are typically operated 24 hours a day.
Since these solutions require a large number of tiles, each having four edges, there are innumerable tile edges in any area of tiles, all of which need to be aligned to present a flat, even tile area which will not cause pedestrians to stumble or trip. In addition, any one of those tile edges may be caught and lifted partially or fully by pedestrian traffic, or more likely, by machinery used to clean the surface. Lifting is especially a problem in outdoor areas in the northern latitudes in which the surfaces must be cleared of snow during the winter; the snow clearing shovels or tractors can easily catch a tile edge and lift the tile, necessitating immediate replacement to prevent the creation of a dangerous hazard to both visually impaired and normally sighted individuals. Because tiles are not mechanically fastened, the expansion of materials due to changes in the weather causes the tiles to frequently delaminate from their bonding agents. In outdoor applications, the tiles tend to bleach rapidly, thereby losing some of their visual impact. Accordingly, the tile tactile edge-warning systems have a number of drawbacks which have prevented them from being ideal solutions to the problem.